<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
    <title>简单三栏布局</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: Arial, sans-serif;
            height: 100vh;
            display: flex;
            flex-direction: column;
        }

        header {
            background-color: #333;
            color: white;
            padding: 1rem;
            text-align: center;
        }

        .container {
            flex: 1;
            display: flex;
            flex-wrap: wrap;
        }

        aside.left {
            width: 200px;
            background-color: #f4f4f4;
            padding: 1rem;
        }

        main {
            flex: 1;
            padding: 1rem;
            background-color: #fff;
        }

        aside.right {
            width: 200px;
            background-color: #eaeaea;
            padding: 1rem;
        }

        footer {
            background-color: #333;
            color: white;
            padding: 1rem;
            text-align: center;
        }

        /* 响应式设计 */
        @media (max-width: 768px) {
            .container {
                flex-direction: column;
            }
            aside.left, aside.right, main {
                width: 100%;
            }
        }
    </style>
</head>
<body>

<header>
    <h1>我的网站标题</h1>
</header>

<div class="container">
    <aside class="left">
        <h2>左侧菜单</h2>
        <ul>
            <li>首页</li>
            <li>关于我们</li>
            <li>联系我们</li>
        </ul>
    </aside>

    <main>
        <h2>主要内容区域</h2>
        <p>这里是页面的主要内容。</p>
    </main>

    <aside class="right">
        <h2>右侧广告</h2>
        <p>这里是推荐内容或广告位。</p>
    </aside>
</div>

<footer>
    <p>© 2025 我的公司 版权所有</p>
</footer>

</body>
</html>